Dual-Rectifier Power Supply With Main and Auxiliary DC Protection
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Solution Overview
Problem
The existing power supply systems for outdoor units of air conditioners face challenges in detecting and protecting both main and auxiliary DC voltages from voltage fluctuations, leading to potential overvoltage issues and interference between these voltages, especially when electrolytic capacitors are omitted to reduce size and cost.
Innovation Solution
A power supply apparatus with separate main and auxiliary rectifier circuits, including a DC voltage detection circuit that monitors both voltages, and switches to control power flow, using capacitors and diodes to absorb and smooth voltage fluctuations, ensuring protection and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common AC power supply feeds both main and auxiliary rectifier circuits, then fewer parts are needed and design is simplified, but voltage fluctuations in the AC power supply can cause overvoltage in both main DC voltage and auxiliary DC voltage, requiring additional protection circuits
Solution Approach 1:
The power supply system is segmented into two independent rectifier circuits: a main rectifier circuit for driving the compressor and an auxiliary rectifier circuit for controlling the outdoor unit. Each circuit has its own protection mechanism, allowing independent operation and protection against overvoltage conditions.
Solution Approach 2:
A diode is introduced as an intermediary component between the auxiliary rectifier circuit and the DC bus. This diode prevents reverse current flow from the main DC bus to the auxiliary rectifier circuit, protecting the auxiliary circuit from overvoltage caused by main circuit fluctuations.
2Ease of operation
If a power switch is provided on the AC input side of the main rectifier circuit to stop main DC voltage supply in compressor-stopped situations, then the main power supply is controlled, but the auxiliary rectifier circuit continues to receive AC voltage which may cause overvoltage in auxiliary DC voltage
Solution Approach 1:
A diode is placed in series with the auxiliary rectifier circuit to act as a one-way valve for current flow. When the main DC voltage is interrupted, this diode prevents reverse current from flowing back into the auxiliary rectifier circuit, thereby protecting it from overvoltage conditions even though the AC input continues.
Solution Approach 2:
The potential harmful effect of continued AC voltage to the auxiliary rectifier circuit is converted into a beneficial protection mechanism. The diode's reverse blocking characteristic naturally prevents overvoltage without requiring active control or additional switching components in the auxiliary circuit.
3Weight of stationary object
If electrolytic capacitors are omitted from the power supply circuit to reduce size and cost, then the apparatus becomes more compact and economical, but voltage fluctuations are not adequately absorbed leading to overvoltage issues
Solution Approach 1:
The invention replaces expensive and bulky electrolytic capacitors with simpler, more compact components such as diodes and small capacitors. While electrolytic capacitors provide good voltage smoothing, they are replaced by a combination of rectifier circuit design and protective components that achieve adequate voltage stabilization with reduced size and cost.
Solution Approach 2:
Diodes are used as intermediary components to manage voltage fluctuations without requiring large energy storage capacitors. The diodes control current flow direction and prevent voltage spikes from propagating through the circuit, providing protection against overvoltage conditions while maintaining a compact design.
4Reliability
If separate detection circuits are provided for both main DC voltage and auxiliary DC voltage, then overvoltage in either circuit can be detected, but the device complexity increases
Solution Approach 1:
The detection system is designed with multi-functionality where a single detection circuit can monitor both the main DC voltage and auxiliary DC voltage. The detection circuit responds to overvoltage conditions in either circuit by generating a stop signal that halts operation of the power supply apparatus, eliminating the need for separate dedicated detection circuits for each voltage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively detects and protects both main and auxiliary DC voltages from overvoltage and overcurrent conditions, reducing size and cost while preventing interference, ensuring reliable operation of the air conditioner components.
Implementation Method 1
a first capacitor (107) that absorbs a switching ripple of the inverter
Implementation Method 2
the auxiliary rectifier circuit includes a second capacitor (110) that smooths the auxiliary DC voltage
Implementation Method 3
further includes a diode (111) having an anode connected to a high-potential side end of the first capacitor and a cathode connected to a high-potential side end of the second capacitor
Data Source
AI summary
Provided is a technique of detecting not only a main DC voltage but also an auxiliary DC voltage to protect a main rectifier circuit and an auxiliary rectifier circuit. A main power supply circuit drives a load. A main rectifier circuit receives an AC voltage through a first switch to supply the main power supply circuit with a main DC voltage. The first switch is turned off when an overcurrent flows through the main power supply circuit or the load is an overload for the main power supply circuit. A control circuit is supplied with operating power from an auxiliary power supply circuit. An auxiliary rectifier circuit receives the AC voltage while bypassing the first switch to supply the auxiliary power supply circuit with an auxiliary DC voltage. A DC voltage detection circuit detects the main DC voltage and the auxiliary DC voltage.